Just spent a few frustrating days trying to get Line 6 usb drivers for Helix and Variax to load successfully. Admittedly I hadn't connected either to my PC for a while, so a lot could have changed in that time. To cut a long story short, the resolution for me has been to turn off Memory integrity in Core isolation in the Windows Defender Security Centre. Neither my audio interface nor phone had problems, so in my limited sample set only the Line 6 drivers were struggling.
Is this a known phenomenon? Should the drivers load with Memory integrity enabled? In both cases the drivers are the current versions (22.214.171.124 and 126.96.36.199 for Helix and Variax respectively). I tried earlier Helix drivers but they had the same problem. My OS is Windows 10 Home, Version 1803.